Rambus Inc. (RMBS) experienced a significant after-hours plunge of 16.85% following the release of its fourth-quarter financial results. The sharp decline occurred in the post-market session as investors digested the company's earnings report and forward guidance.

While Rambus reported strong Q4 2025 results with adjusted earnings per share of $0.68 meeting analyst expectations and revenue of $190.2 million beating estimates and growing 18% year-over-year, the market reaction was negative. The downturn appears driven by the company's outlook for the first quarter of 2026, which includes product revenue guidance between $84 million and $90 million. This represents a potential sequential decline from the record quarterly product revenue of $96.8 million achieved in Q4 2025.

The semiconductor technology company also provided Q1 licensing billings guidance of $66-72 million and operating costs projection of $121-117 million. Despite generating record quarterly cash from operations of $99.8 million in Q4, investors focused on the softer forward-looking statements, leading to the substantial after-hours selloff.